As I said a few times on this blog, this question is very common now and even if it's a rhetorical one, it's quite useful to think with because it generates a healthy debate about the diversity of voices who speak on behalf of Islam. Link TV is continuing its series on Who Speaks for Islam with some interesting guests from actors, authors, tv producers, Hollywood screenwriters, comedians to pollsters. I also came across this passionate debate between Irshad Manji and Dalia Mogahed (from last year) on Fora TV about this very question on religious authority and the proliferation of Muslim voices.